Sister needs to take own financial responsibility from parents

Dear Annie: My older sister, "Susie," is 33 and has been receiving financial support from my parents for more than a decade. They give her money outright and also pay her car insurance, health insurance and other bills. Susie does not work. She’s in a master’s program, but it is unclear whether she will finish. My mother believes she needs to help Susie, as she has had mental illness issues throughout her adulthood.